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Help! Spark plugs damaged but hold torque!

Discussion in '2nd Gen 4Runners (1990-1995)' started by Clueless17, Jun 17, 2023.

  1. Jun 17, 2023 at 7:29 PM
    #1
    Clueless17

    Clueless17 [OP] New Member

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    What's goin on everyone I'm brand new to the 4runner life. Just bought a used 93 4runner and decided to do a little tune up. So I'm changing spark plug number 6 and it gets tighter as I'm unscrewing it. In a fit of stupidity and lack of better judgment, I grabbed my breaker bar, slapped a cheater pipe on that bad boy and just obliterated that spark plug. I snapped it half with all the porcelain out and just the threads remaining in the head. I drilled out the crush washer so I was left with just the threads. I grabbed my M14 tap and drilled into the sparkplug threads and head threads the closest I had to the corresponding size which was 13mm. (M14 tap calls for 12.8mm I believe) I tapped it and now as I'm putting in the plug to see if it fits, I can tell the threads are damaged and maybe a little shallow because I didn't use the exact required size drill bit, but it holds torque! (Approx. 18-21 ft lbs). My question is, how screwed am I? Is it okay as long as it holds torque?should I just helicoil or timesert it?

    The truck has 250k miles on it so I'm not too worried about longevity. Thanks for your insight
     
  2. Jun 18, 2023 at 3:02 AM
    #2
    AuSeeker

    AuSeeker Old As Dirt

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    If it torques properly it should stay tight, the crush washer should make sure it's sealed and holds compression, but what I would be most concerned with is metal shavings down in the cylinder from drilling and tapping, unless you use some axle grease on the drill and tap to help keep the metal shavings from dropping down into the cylinder.

    In the future when a bolt or any threaded item gets tighter when removing it you should loosen it until it get tight then reverse and tighten it a few turns until it gets loose and then try removing it again, rinse and repeat until you get it out, what happens when you do it this way is, is in this case as you were removing the plug carbon (or rust if on a bolt) on the threads jammed up in the threads and the plug became tighter, by removing and then tightening the plug it will allow some of the carbon to fall out of the threads making so you can remove the plug a bit further each time you reverse the process.
     
    Clueless17[OP] and Wvmoonshiner like this.
  3. Jun 18, 2023 at 8:38 AM
    #3
    Clueless17

    Clueless17 [OP] New Member

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    Thanks for the advice! I didn't have grease but I used cutting oil on the tap, a lot of the shavings were stuck on it but for sure some might've fallen inside, so I ordered a long nose airgun tip to blow it out before I start it up. I also unplugged the distributor and let the starter crank it a bit so the cylinder could spit out what it could. Not satisfied though so I'm gonna make sure to blow it out good.

    And yeah lesson learned, wiggling it in and out is the way to go. I appreciate your time
     
    Curt56 likes this.
  4. Jun 18, 2023 at 8:46 AM
    #4
    morfdq

    morfdq New Member

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    You’re good. I commend you on your quick thinking
     

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